Electrical relay



March 16, 1943. A. J. SORENSEN 2,313,973

ELECTRICAL RELAY Filed May 31, 1941 W Cbzzzpal (from? L IN b JTOR 15 1 3Andrew maven.

19 BY 5 1 Conf olauoazz HIS ATTORNEY Patented Mar. 16, 1943 "UNITEDSTATES PATENT OFFICE ELECTRICAL RELAY Andrew J. Sorensen, Edgewood,P-a., assignor to The Union Switch & Signal Company, Swissvale, Pin, acorporation of Pennsylvania Application May 31, 1941, Serial No. 395,907

15Claims.

My invention relates to a relay system and particularly to means forrendering the operation of a relay more positive than has heretoforebeen possible.

This application is a continuation-in-part of my application Serial No.361,929, filed October 19, 1940.

As usually constructed a relay has a core, a winding mounted on thecore, and a movable armature which is attracted to the core onenergization of the relay winding. In addition, the armature has mountedthereon, or otherwise associated therewith, movable contacts whichengage stationary contacts on movement of the relay armature to itspicked-up position. Normally either or both the movable and stationarycontacts are mounted on springs, while these contacts are arranged sothat they engage when the relay armature moves part of the way to itspicked-up position, and so that on further movement of the relayarmature towards its picked-up position the contact springs aredeflected and the contacts are held firmly in enagement.

The force exerted to move the relay armature from its released to itspicked-up position on energization of the relay Winding varies inverselyas the square of the distance between the core and the armature.Accordingly, when the armature is in its released position, at whichtime there is considerable space between the relay core and armature,the force exerted by the flux in the core on the armature is relativelysmall, and current of relatively high value must be supplied to therelay winding before the flux in the core is built up to a value highenough to attract the relay armature to the core, that is to move therelay armature from its released to its picked-up position.

Similarly, when the relay armature is in its picked-up position, thereis relatively little space between the relay armature and core and theflux in the core exerts relatively great force on the armature tomaintain it in the picked-up position. Accordingly, when the relayarmature is in its picked-up position, it will remain in that positionuntil the current in the relay winding is reduced to a much lower valuethan was necessary to effect picking up of the relay armature.

This difference between the pick-up and release values of a relay isobjectionable in some situations, and it has been suggested heretoforethat these values can be made more nearly equal by arranging the circuitof the relay winding so that on movement of the relay armature from itsreleased position to its picked-up position the degree of efiectiveenergization of the relay winding is reduced to a value slightly inexcess of that necessary to maintain the relay 'duced to a predeterminedvalue.

armature picked up. This reduction in the degree of energization of therelay winding on picking up of the relay armature may be accomplished byconnecting a resistance in series with the relay winding, by shortcircuiting some of the turns of the relay winding, or by any othersuitable means.

Accordingly, with this arrangement on a subsequent small reduction inthe value of the current supplied to the circuit of the relay windingthe armature of the relay becomes released. On release of the relayarmature the degree of effective energization of the relay winding isincreased and the relay armature is thereafter picked up on a smallincrease in the value of the current supplied to the circuit of therelay windmg.

The arrangement described above operates to greatly reduce thedifference between the pickup and release values of a relay, but evenwith the best possible arrangement of the equipment a considerabledifference between these values must be maintained to insure properoperation of the relay.

A complicating factor in the operation of a relay of this type is theeffect of the contact springs. On movement of the relay armature farenough towards its picked-up position to cause engagement of the movableand fixed contacts further movement of the relay armature is resisted bythe contact springs. If when the relay armature moves far enough towardsits picked-up position to cause the movable contacts to engage thestationary contacts the effective energization of the relay winding isreduced by inserting a resistance in series with the winding, orotherwise, the flux density may be reduced to such a low level thatinsufficient force is exerted on the relay armature to move it to itspicked-up position against the opposition of the contact springs.Accordingly, the relay armature may not complete its movement to itspicked-up position but will remain in the position in which the movableand fixed contacts lightly engage.

In like manner when the relay armature moves from its picked-up positiontowards its released position, initial movement of the armature isassisted by the contact springs so that the armature; will move towardsits released position whenthe flux in the relay core is re- As the relayarmature moves towards its released position, the force exerted by thecontact springs decreases, While when the armature moves to the positionin which the movable and fixed contacts barely engage, or aredisengaged, the contact springs cease to exert force on the relayarmature to move it to its released position and the relay armature mayremain in this position and not complete its movement to the releasedposition. This is particularly true if when the relay armature moves tothe position at which the fixed and movable contacts disengage thedegree of energization of the relay winding is increased so that thereis an increase in the flux in the relay core.

It has been found that when relays of the type described are energizedwith current of an intermediate value, the contacts will chatter orvibrate, that is, the movable contacts of the relay intermittentlyengage and become disengaged from the relay stationary contacts. Thiscondition is objectionable because as the voltage of the currentsupplied to the relay is gradually increased or decreased, there is arange during which operation of the relay is uncertain.

It is an object of my invention to provide a relay incorporating meansto insure that on movement of the relay contacts towards their releasedor picked-up positions they will complete their movement to suchpositions.

A further object of my invention is to provide a relay having littledifference between the pickup and release values and incorporating meansto insure that the relay armature will always move all of the way to itspicked-up and released positions.

Another object of my invention is to provide an improved relay.

Other objects of my invention and features of novelty will be apparentfrom the following description taken in connection with the accompanyingdrawing.

I shall describe five forms of equipment embodying my invention, andshall then point out the novel features thereof in claims.

In the drawing Fig. l is a diagram showing speed responsive apparatusemploying a relay provided by this invention,

Fig. 2 is a diagram of a section of railway track provided with trackcircuit apparatus employing a relay embodying my invention,

igs. 3, 4, and 5 are diagrams of modifications which may be employed inplace of the equipment shown in Fig. 1.

Similar reference characters refer to similar parts in each of theseveral views.

Referring to Fig. 1 of the drawing, there is shown therein a directcurrent generator G of a type which is adapted to supply current at avoltage which is substantially proportional to the speed at which thegenerator armature is rotated. The generator armature may be driven froma suitable member, such as the axle of a railway vehicle, which isoperated at varying speeds, while the equipment of which the generatorforms a part may be employed to control the brakes on the vehicle or toindicate when the vehicle is exceeding a predetermined speed.

A complete brake control system of the type in which the relay providedby this invention may be employed is shown in my application Serial No.342,9 l1, filed June 28, 1940, for Brake control means (Westinghouse AirBrake Company Case 4745).

The equipment shown in Fig. 1 of the drawing includes in addition to thegenerator G, a relay R, a transformer T, and an electroresponsive deviceM. The device M may be a magnet valve device for controlling the supplyof fluid under pressure to brake cylinders, not shown, or it may be alamp or any other device which it is desired to govern in response tothe vehicle speed.

The relay R is provided with a first winding l0 and a second winding I Iwhile the transformer 'I has a primary winding l3 and a secondarywinding I4.

The equipment is shown in the condition which it assumes when thevehicle is standing still or is moving at a slow speed. When the vehicleis primary winding l4 of the transformer T, andcontact [9 interrupts thecircuit of thedevice M';

On an increase in the speed of the vehicle there is an increase in thevoltage of the current supplied from the generator G to the winding H)of the relay R, and a corresponding increase in the current flowingthrough the winding of the relay R. When the speed of the vehicleincreases to a predetermined value, such as 50 miles an hour, thecurrent in the winding I0 is increased to a value high enough to causesufiicient flux to be developed in the relay core to attract the relayarmature to the core.

As usually constructed, the relay armature and contacts are arranged sothat the movable con tacts do not become disengaged from their baclrpoints of contact until the armature has moved a substantial part of theway towards its pickedup position.

Accordingly, on picking up of the relay armature the circuit'shun'tingthe resistor 16 is not interrupted until after the relay armature movesa substantial part of the distance towards its picked-up position, whilebefore the contact I5 interrupts the circuit which it controls the airgap separating the relay core and armature will have been substantiallyreduced so that the force acting on the armature to move it towards thepicked-up position is materially increased. As a result, even though oninterruption of the circuit shunting the resistor [6 there is areduction in the current in the winding l0, suflicient force is exertedon the relay armature to insure-that it will continue to move towardsits picked-up position far enough for the movable contacts to,en-, gagetheir front contacts.

When contact I8 engages its front contact, the circuit is establishedfor supplying energy from a local source of direct current, such as abattery, not shown, to the transformer primary winding 13. As a resultof the supply of energy to the winding l3, an impulse of energy isinduced in the transformer secondary winding HI and is suppliedtherefrom to the winding H of the relay R. The impulse of energysupplied to the relay winding II is of such polarity that the fluxdeveloped in the relay core by this energy is of the same polarity asthe flux developed by the energy in winding 10. Accordingly, on thesupply of the impulse of energy to the winding H there is an increase inthe flux in the relay core and an increase in the force tending to movethe relay armature to its picked-up position.

The various parts of the equipment are ar ranged and proportioned sothat the force developed on the supply of the impulse of energy to thewinding H is great enough to move the relay armature all of the way toits picked-up position against the biasing means and against the contactsprings.

The impulse of energy induced in the transformer secondary winding I4 isof momentary duration only and terminates as soon as the current in thetransformer primary winding builds up to the full value of the currentsupplied from the current source.

On termination of the impulse of energy in the winding H of relay R theflux density of the relay core decreases. However, before this decreaseoccurs the relay armature will have been moved all of the way to itspicked-up position and the air gap between the relay core and armaturewill have been reduced to the minimum with the result that the maximumforce is exerted on the relay armature to maintain it in its picked-upposition. I

The various parts of the equipment are arranged so that, when the relayarmature is in its picked-up position, the flux developed in the relaycore by the energy supplied to the winding l through the resistance I6is effective to maintain the relay armature picked up as long as thecurrent supplied to winding I0 is equal to or greater than the valuepresent when the vehicle speed exceeds the predetermined speed.

As long as the armature of the relay R is picked up, contact I9establishes the circuit of the electro-responsive device M, whilecontact I8 maintains the circuit of the transformer primary winding.

As long as the speed of the train exceeds the predetermined rate, thevalue of the current supplied by the generator G is high enough to maintain the relay armature picked up. However, when the speed of the trainis reduced, the voltage of the current supplied by the generator isreduced, and when this falls to a predetermined amount, the energysupplied through the resistor IE to the winding ID of the relay B doesnot develop suflicient flux in the relay core to main tain the relayarmature picked up, and the armature moves towards its releasedposition. Initial movement of the armature is assisted by the contactsprings, but as the armature moves from its picked-up position, theeffect of these springs is reduced, while, when the armature moves farenough towards the released position for the movable contacts to becomedisengaged from the front contacts, the contact springs cease to exertforce on the armature.

As the armature moves towards its released position, the air gap betweenthe relay armature and core is increased so that the force exerted onthe armature by the flux in the relay core is reduced. As soon as thearmature moves far enough towards its released position for contact l8to be disengaged from the associated stationary contact, the circuit ofthe transformer primary winding is interrupted and the flux in thetransformer core collapses with the result that an impulse of energy isinduced in the transformer secondary winding and is supplied therefromto the relay winding I l. The polarity of this impulse of energy is suchthat it tends to develop in the relay core flux of the polarity oppositeto that developed by the energy supplied to the winding l0.

Accordingly, on the supply of the impulse of energy to the winding IIthere is a decrease in the flux in the core of the relay and a corresponding decrease in the force opposing movement ofthc relay armature.towa ds t e ed position and the armature quickly moves all of the way toits released position.

When the relay armature moves far enough towards its released positionfor contact 5 to engage its back point of contact, the circuit shuntingthe resistor I6 is established and there is an increase in the energysupplied to the winding ll] of the relay R and a corresponding increasein the flux in the relay core.

The impulse of energy supplied to the winding H is of momentaryduration, and after its termination the flux in the relay core is builtup by the energy in the winding 10. However, before this increase in theflux in the relay core occurs the relay armature will have moved all ofthe way to its released position and the air gap between the armatureand core will have been increased to the maximum so that the forceexerted on the armature by the flux in the relay core is at the minimum.Accordingly, even though the flux in the relay core increases, thearmature will remain in its released position until the current suppliedfrom the generator G to the winding is increased to a predeterminedvalue.

It will be seen that with the relay provided by this invention, onpicking up of the relay armature a resistance is inserted in the circuitof the relay winding to render the release value of the relay nearly thesam as the pick-up value. In addition, as soon as the relay armaturepicks up far enough for its front contacts to engage, an impuse ofenergy is supplied to the relay to insure that the armature willcomplete its movement to its picked-up position. Similarly, on releaseof the relay armature the resistance is removed from the circuit of therelay winding, while an impulse of energy is supplied to the relay toinsure that the relay armature will complete its movement to itsreleased position.

It will be seen, therefore, that operation of the relay is definite andpositive, and that once the relay armature starts to move to eitherposition it will complete its movement to that position. This eliminateschattering and fluttering of the relay contacts and thereby makes itpossible to arrange the relay and associated apparatus so that there islittle difference between the pick-up and release values of the relay.

Referring to Fig. 2 of the drawing, there is shown therein a stretch ofrailway track having track rails l and 2 over which traffic normallymoves in the direction indicated by the arrow, that is, from left toright. The track rails have insulated rail joints 3 therein to dividethe track stretch into track sections. One such section is shown and isdesignated section 2flT.

The track section has at the exit end thereof a source of track circuitenergy in the form of a track battery TB which is connected across thesection rails, While a suitable resistor 2| is connected in series withthe track battery.

A primary track relay TRA and a secondary track relay TRB are connectedacross the section rails at the entrance end of the section. The relayTRB may be employed to control a signal, not shown, for the tracksection, or it may be employed to control any other apparatus which itis desired to govern in accordance with occupancy of the track section.

The equipment is shown in the condition which it assumes when the tracksection is vacant. At this time energy from the track battery TB feedsover the track railsto the windings .of relays TRA and THE and maintainsthe contacts of the relay TRA picked up. The circuit for energizingthese relays is traced from one terminal of the track battery TB overtrack rail l, winding 23 of relay TRB, winding of relay TRA, resistance24, track rail 2, and resistance 2| to the other terminal of th trackbattery.

As the winding of relay TRA is energized, its contact 25 is picked upand establishes a circuit to supply energy from a local source of directcurrent, not shown, to the winding 26 of relay TRB. The windings 23 and26 of relay TRB when energized assist each other in maintaining therelay contacts picked up, and at this time the contacts 28 and 29 arepicked up. As contact 28 is picked up, the circuit which it controls forshunting the resistance 24 is interrupted, while as contact 29 is pickedup, the control circuit is established.

When a train enters the track section, the wheels and axles of thevehicles comprising the train shunt the track relays TRA and TRB andreduce the energy in the winding of the relay TRA to such a low valuethat the relay armature releases. When the armature moves .far enoughtowards its released position for contact 25 to become disengaged fromthe associated stationary contact, the circuit of the winding 26 is interrupted.

On deenergization of the winding 26 of relay TRB there is a collapse ofthe flux in the relay core. As the flux in the relay core reduces,energy is induced in the Winding 23, and is supplied therefrom to thewinding of relay TRA. The polarity of the impulse of energy supplied tothe relay TRA from the winding 23 is opposite to that supplied to thewinding of relay TRA over the track rails, and therefore this impulse ofenergy operates to create in the core of relay TRA flux of the polarityopposite to that present in the core. Accordingly, any flux in the coreof relay TRA produced by energization of the relay winding by currentsupplied from the track battery is quickly dissipated and the armatureof the relay is certain to complete its movement to its releasedposition.

On the collapse of the flux in the core of the relay 'IRB there is areduction in the force tending to hold the relay armature in itspicked-up position, and, when the flux density reduces to apredetermined value, the relay armature moves towards its releasedposition and contact 28 establishes the circuit shunting the resistor 24with the result that there is an increase in the current supplied fromthe track battery TB to the relay TRA.

However, before the ilux in the core of the relay TRB reduces far enoughfor the armature of this relay to become released and establish thecircuit shunting the resistor 24, an impulse of energy of substantialvalue will have been supplied to the relay IRA and the armature of thisrelay will have completed or substantially completed its movement to itsreleased position, and the air gap between the relay core and armaturewill be substantially at the maximum so that the flux in the relay coreexerts the minimum force on the relay armature. Accordingly, on theincrease in the current in the winding of relay 'I'RA which takes placeon shunting of the resistance 24 the relay armature remains released.

As a result of the release of the armature of the relay TRB, contact 29opens the control circuit.

When the train vacates the track section, the shunt provided by thevehicles of the train removed and energy from the track battery feeds tothe relays TRA and TRB. At this time the resistor 24 is shunted by thecircuit controlled by contact 28 of relay TRB so suflicient energy issupplied to the winding of relay TRA to pick up the armature of thisrelay. When the armature moves far enough towards its picked-up positionfor contact 25 to engage the associated stationary contact, energy issupplied to the winding 26 of relay TRB.

On the supply of energy to the winding 26 of relay TRB the flux in therelay core builds up and an impulse of energy is induced in the winding23 and is supplied therefrom to the winding of relay TRA. This impulseof energy is of the same polarity as that of the energy supplied to therelay 'I'RA from the track battery so that there is a momentary increasein the flux in the core of relay TRA, and a corresponding increase inthe force tending to move the armature of relay TRA all of the way toits picked-up position against the resistance of the contact springs.

When the flux in the core of relay 'IRB builds up a predeterminedamount, the armature of this relay picks up and contact 28 interruptsthe circuit shunting the resistor 24 so that there is a reduction in thecurrent supplied to the relay TRA. On this reduction in the current inthe winding of relay TRA there is a reduction in the flux in the relaycore and a corresponding reduction in the force tending to hold therelay armature picked up. However, before this reduction in the forceacting on the relay armature takes place the relay armature will havebeen moved all of the way to its picked-up position, or substantiallyall of the way thereto, and the space between the relay armature andcore will have been reduced to the minimum so that the maximum force isexerted on the relay armature to maintain it picked up.

Accordingly, on the reduction in the current in the winding of relayTRA, which occurs on termination of the impulse of energy from winding23 of relay TRB and on inclusion of the resistor 24 in the circuit ofthe relay winding, the relay armature will remain in its picked-upposition and contact 25 will maintain the circuit of the winding 26 ofrelay TRB so that contact 29 establishes the control circuit. Inaddition, contact 28 interrupts the circuit shunting the resistor 24 andthe relay T'RA will release on a small reduc" tion in the energysupplied thereto.

From the foregoing it will be seen that the arrangement shown in Fig. 2is especially eflicient since on picking up of the armature of relay TRAfar enough for its front contacts to engage, a portion at least of theimpulse of energy from the winding 23 of relay TRB is supplied to therelay TRA before the resistance 24 is included in the circuit of therelay TRA. Accordingly, current of the maximum value is present in therelay winding and insures movement of the relay armature substantiallyall of the way to its picked-up position before the current in the relaywinding is reduced by the resistance 24.

Similarly, when the relay armature moves far enough towards its releasedposition for contact 25 to be disengaged from the associated stationarycontact, a portion at least of the impulse of energy from the winding 23of relay TRB is supplied to the relay TRA before the resistance 24 isshunted. Accordingly, the flux in the core of relay TRA is reduced toinsure movement of the relay armature substantially all of the way toits released position before the current in the relay winding isincreased by shunting of the resistor 24.

Referring to Fig. 3 of the drawing, there is shown therein a modifiedform of apparatus which may be employed in place of that shown inFig. 1. The system shown in Fig. 3 includes a generator G of the typeemployed in the equipment shown in Fig. 1, while the equipment shown inFig. 3 includes relays RA and RB each of which is provided with twowindings. The winding 39 of relay RA is energized by current supplied bythe generator G, while this winding is provided with a tap or connectionat an intermediate point in the winding so that a portion of the turnsof the winding may be short circuited at times to thereby decrease theefiectiveness of the winding.

The equipment of Fig. 3 is shown in the condition which it assumes whenthe vehicle is idle or is moving at slow speed. At this time the voltageof the energy, if any, supplied by the generator G is so low that toolittle energy is supplied to the winding 30 of relay RA to pick up thecontact 3i. Accordingly, the circuit of the windin 32 of relay RB isinterrupted and its contacts 3 and 35 are released. As contact 34 isreleased, the circuit for short circuiting a portion of the winding 30of relay RA is interrupted and the entire winding is energized, while asthe contact 35 is released, the device M is deenergized.

When the vehicle speed is increased to a predetermined rate, such as 50miles an hour, the energy supplied from the generator G to the winding35 of relay RA picks up the contact 3| so that energy is supplied from alocal source of direct current, not shown, to the winding 32 of relayRB. As a result of the supply of energy to the winding 32 of relay RB,an impulse of energy is induced in winding 36 of the relay and issupplied therefrom to the winding 38 of relay RA and assists the winding30 in moving the relay armature to its pick-up position so that thearmature is certain to complete its movement.

In addition, as a result of the supply of energy to th winding 32' ofrelay RB, the armature of this relay picks up and contact 35 completesthe circuit of the device M, while contact 34 establishes the circuitfor short circuiting a portion of the winding 33 of relay RA so thatthereafter a portion only of this winding is energized and there is areduction in the force tending to hold the armature of relay RA pickedup.

The various parts of the equipment are ar ranged so that the portion ofthe winding 30 which continues to be energized after picking up ofcontact S l develops sufficient flux in the relay core to maintain therelay armature picked up as long as the vehicle speed exceeds thepredetermined rate. I

On a subsequent predetermined reduction in the speed of the vehicle thecurrent supplied from the generator G to the winding 36 of relay RA- isunable to maintain the relay armature picked up and the armaturereleases and contact 35 interrupts the supply of energy to the winding32 of relay RB. On deenergization of winding (52 an impulse of energy isinduced e winding and is supplied therefrom to g of relay RA. Theimpulse of energy led to the winding 38 at this time is of such ity thatit decreases the flux in the relay core and thereby insures that thearmature of relay RA will complete its movement to its releasedposition.

On deenergization of the winding 32 of relay RB the armature of thisrelay releases and contac 35 interrupts the circuit of the device M,while contact 34 interrupts the circuit short circuiting a portion ofthe winding 39 of relay RA.

It will be seen that the modification shown in Fig. 3, like those shownin Figs. 1 and 2, incorporates means to render operation of a relaypositive and definite. In the modification shown in Fig. 3 impulses ofenergy are supplied to the winding 38 of the relay RA to insure that therelay armature will complete its movement to its picked-up and releasedpositions, while means is provided for at times short circuiting aportion of the winding 39 of the relay RA to thereby render the releaseand pick-up values of the relay more nearly equal than they wouldotherwise be.

In Fig. l of the drawing there is shown another form of apparatus whichmay be employed in place of that shown in Figs. 1 and 3.

The relay R of the modification shown in Fig. 4 is provided with amake-beiore-break contact which controls a circuit for supplyingimpulses of energy to the winding l I of the relay, while the polarityof the energy supplied over this circuit is controlled by contacts ofthe auxiliary relay RE.

The equipment is shown in the condition which it assumes when thevehicle is idle or is moving at slow speed. At this time the voltage ofthe energy, if any, supplied by generator G is so low that too littleenergy is supplied to the winding ID of relay R to pick up the contactsof this relay. Accordingly, contact 3| of relay R interrupts the circuitof relay RB so that the contacts of relay RB are released and contact 34establishes the circuit shunting the resistance It. Accordingly, thefull voltage of any energy supplied by the generator G is supplied towinding I 0 or relay R.

When the vehicle speed is increased to a predetermined rate, such a 50miles an hour, the energy supplied by the generator G to winding l0 ofrelay R is eiiective to pick up the contacts of this relay. On pickingup of the relay contacts its movable contact 30' engages contact 4i sothat a circuit is established to supply energy of one polarity to thewinding l l and is traced from terminal B of a source of direct currentthrough back contact 44 of relay RB, contacts Ail-GL-AZ of relay R,winding I I of relay R, and back contact of relay RB to terminal C ofthe source. The various parts of the equipment are arranged so that theenergy supplied to winding H of relay R at this time aids the energy inwinding Iii to move the relay contacts to their picked-up positions.Accordingly, after the contacts of relay R have moved far enough towardstheir picked-up positions to cause contact 450 to engage contact i 5'additional force is exerted on the relay contacts tending to move themto their picked-up position.

On further movement of the armature of the relay R subsequent toengagement of contact 40 with contact ll the contact M is moved out ofengagement with contact 12 to thereby interrupt the circuit forsupplying energy to winding l l. Before this occurs, however, the relayarmature will have been moved relatively close to the core of the relayso that the winding it exerts great force on the armature to causethearmature to complete its movement to its picked-up position,

while the inertia of the armature assists in cans ing the armature tocomplete its movement. to the picked-up position.

On picking up of the contacts of the relay R its contact 3| establishesthe circuit for supplying energy to the winding of relay RB, but thisrelay has a slow pick-up characteristic so that its contacts do not pickup until after the contacts of relay R are picked up so that itscontacts 4|42 interrupt the circuit of winding ll of relay R.Accordingly, on picking up of the contacts 44 and 45 of relay RB thereis no possibility that energy of reverse polarity will be supplied tothe winding I I of relay R.

In addition, on picking up of the contacts of relay RB its contact 34interrupts the circuit shunting the resistor i 6 so that this resistanceis included in series with the circuit for supplying energy from thegenerator G to the winding I 01' relay R with the result that there is areduction in the current in this winding. Before this reduction occurs,however, the armature of relay R has completed its movement to itspicked-up position, and the reduced current in the winding It iseffective to maintain the relay contacts picked up assuming that thetrain speed has not been reduced.

On picking up of the contacts of relay RB its contact 35 completes thecontrol circuit which may be employed to perform any desired function.

On a subsequent slight reduction in the speed of the train the currentsupplied from the generator G through the resistance IE to the windingIf] of relay R is ineffective to maintain the relay contacts picked up.Accordingly, the contacts 01 the relay release, and when they move apart of the distance towards their released position, contact 4i engagescontact 42 and a circuit is established to supply energy to winding H ofrelay R. The energy supplied to this winding at this time is of theopposite polarity from that supplied to the winding on picking up of therelay contacts since at this time the contacts of relay RB are pickedup. The circuit for supplying energy to the winding l I is traced fromterminal B through front contact 45 of relay RB, winding 1 l of relay R,contacts 42-4l40 of relay R, and front contact 44 of relay RB toterminal C of the source.

The energy supplied to the winding H at this time is of such polaritythat the force exerted by winding H opposes that exerted by winding I!)so that on energization of winding ll there is a substantial reductionin the force exerted on the armature to hold it picked up and thebiasing means causes the armature to move all of the way to its releasedposition.

On further movement of the relay armature towards its released positionsubsequent to engagement of contact 4| with contact 42, contact 40becomes disengaged from contact 4i and interrupts the circuit of thewinding H. Before this occurs, however, the relay armature will havemoved substantially all of the way to its released position so that theair gap between the armature and core is increased to such an extentthat the winding it! exerts reduced force on the armature, while theinertia of the armature assists in causing the armature to complete itsmovement to its released position.

On release of the contacts of relay R its contact 3| interrupts thecircuit of relay RB so that the contacts of this relay release. Thisrelay is of a type the contacts of which are slow to release so that itscontacts remain picked up until the contacts of relay R have moved farenough towards their released position for contact 40 to becomedisengaged from contact 4| and thereby interrupt the circuit of windingll of relay R.

On release of the contacts of relay RB contact 34 establishes thecircuit shunting the resistor 15 so that there is an increase in thecurrent supplied to winding l I) of relay R, but this is insufficient topick up the relay contacts assuming the train speed to have remainedconstant.

In addition, on release of the contacts of relay RB contact 35interrupts the control circuit.

From the foregoing it will be seen that this modification provides meansefiective on movement of the contacts of the principal relay R towardseither position to supply to the winding l I of the relay a momentaryimpulse of energy of such polarity as to assist movement of thearmature. This energy overcomes the effect of the changes in the forceexerted on the armature by the contact springs and insures that therelay armature will complete its movement to either position.

In Fig. 5 of the drawing there is shown another modification which I mayemploy. This modification employs a condenser Q which is connected inseries with the winding ll of the relay R.

When the vehicle is standing still or is traveling at a low speed, theenergy supplied from the generator G to the winding 10 of relay R isineffective to pick up the relay contacts. Accordingly, the contacts ofrelay R are released and contact 15 establishes the circuit shunting theresistor R, while contact I9 interrupts the control circuit.

At this time condenser Q is charged over the circuit which is tracedfrom terminal 13 or a source of direct current through back contact 41of relay R to one element of the condenser, and from the other elementof the condenser through the winding H of relay R and back contact 48 ofrelay R to terminal C. The condenser Q prevents flow of direct currentin this circuit so that winding II does not exert any force on the relayarmature.

On a predetermined increase in the train speed the energy supplied fromthe generator G to the winding I0 is increased to a value effective topick up the relay contacts. On this movement of the relay contacts thecircuit traced above for charging the condenser Q is interrupted and acircuit is established to supply energy of the opposite polarity to thecondenser. This circuit is traced from terminal B through front contact48 of relay R, and winding ll of the relay to one element of thecondenser. and from the other element of the condenser through frontcontact 41 of relay R to terminal C.

On establishment of this circuit energy flows through the winding ll ofrelay R as a. result of the discharge of the energy previously stored inthe condenser and as a result of charging up of the condenser withenergy of the opposite polarity. This flow of energy is of momentaryduration only and ceases when the condenser is charged.

The various parts of the equipment are arranged so that the energy whichflows in the winding II at this time flows in such direction that theforce exerted by winding II on the relay armature assists that exertedby winding ID to pick up the relay armature. Accordingly, the relayarmature moves all of the Way to its picked-up position, and thereafterremains in that position although contact l5 interrupts thec'ircuitshunting the resistor l-B so that less energy is supplied to thewinding 1 0.

When the contacts of relay R are picked up, contact [9 establishes thecontrol circuit.

On a subsequent reduction in trainspeed the energy supplied to windingl-O- through the resist'ance I6 is too low in value to maintain therelay contacts picked up. On release of the contacts 41 and 48 thecircuit traced above for supplying energy to the condenser Q isinterrupted and a circuit including back contacts I! and 48 isestablished to supply energy of the opposite polarity to the condenser.Accordingly, energy fiows through the winding H of relay R both as aresult of discharge of the condenser and of charging of the condenserwith energy of the, opposite polarity. The energy flowing through hewinding H of relay R is of such polarity that the force exerted by thewinding on the relay armature opposes that,

exerted by winding It and the armature completes its movement to itsreleased position even though contact l establishes the circuit shuntingthe resistor It so that there is an increase in the current supplied tothe winding Hi.

It will be seen, therefore, that the modification shown in Fig. 5, likethe other modifications, operates so that on movement of the relaycontacts towards either of their positions there is supplied to a windinof the relay a momentary impulse of energy of such polarity as to insuremovement of the relay armature all of the way to that position.

While the invention has been illustrated and described in connectionwith speed responsive means and with a track circuit, the invention isnot limited to use in these fields and may be employed wherever it isdesired to have a relay operate positively when energized with currentof variable voltage.

Although I have herein shown and described only five forms of relaysystems embodying my invention, it is understood that various changesand modifications may be made therein within the scope of the appendedclaims Without departing from the pirit and scope of my invention.

Having thus described my invention, what I claim. is:

1. In combination, a relay, meansfor supplying to a Winding of saidrelay energy which at one time is of a value high enough to effectmovement of the relay contacts from their released to their picked-uppositions and at another time is of a value too low to mainta n therelay contacts picked up, a first and asecend winding inductivelycoupled together, means-for supplying energy from said second winding toa winding of said relay a' source ofdirect current, and a circuitcontrolled by a contact of said relay for supplying energy from saidsource to. said first Winding, whereby on movcmentoi the relay contactsfrom one of their'positions to the other there is a change inenergization of said first winding and animpulse of energy is induced insaid second winding and is supplied therefrom to said relay winding, theequipment being arranged so that on movement of the relay contactstowards either of their two positions the im 'iulse of energy suppliedto the relay winding from said second winding is of such polarity astoassist movement of the relay contacts to such position. I I I *2. Incombination, a relay having a winding andhaving armature which when initemleased position: is moved to its picked-up posi tion when saidwinding is energized to a predetermined degree, a supply circuit overwhich energy may be supplied to said relay winding, means for supplyingto saidsupply circuit energy which at one time is of a first value andis effective to energize said relay winding to said predetermined degreeand which at other times is of a second or lower value and isineffective to energize said relay winding to said predetermined degree,means operative when said relay armature is in its picked-up position tomodify the circuit of the relay winding so that when energy of saidfirst value is supplied to said supply circuit energization of the relaywinding is reduced to a degree slightly higher than that necessary tomaintain the relay armature in its pickedup position, whereby when saidarmature is in its picked-up position it becomes released on a smallreduction in the value of the current supplied to said supply circuit, afirst and a second winding inductively coupled together, means forsupplying energy from said second winding to a winding of said relay, asource of direct current, a circuit governed by said relay armature forsupplying energy from said source to said first Winding, whereby onmovement of the relay armature from either of its positions to the otherof its positions there is a change in energization of said first windingand an impulse of energy is induced in said second winding and issupplied therefrom to said relay Winding, the equipment being arrangedso that on movement of said relay armature towards either of its twopositions the impulse of energy supplied to the relay winding from saidsecond winding is of such polarity as to assist movement of the relayarmature to such position to thereby insure that the relay armature willcomplete its movement to such position.

3. In combination, a principal relay having a winding and having anarmature which when in its released position is moved to its picked-upposition when said winding is energized to a predetermined degree, asupply circuit over which energy may be supplied to said relay winding,

means for supplying to said supply circuit energy Which at one time isof a first value and is effective to energize said relay winding to saidpredetermined degree and which at other times is of a second or lowervalue and is ineffective to energize said relay winding to saidpredetermined degree, an auxiliary relay having a first and a secondwinding, means for supplying energy from said auxiliary relay secondwinding-to a winding ofsaidprincipal relay, means operative in oneposition of the armature of said auxiliary reiay to modify the circuitof the winding of the principal relay so that when energy of said firstvalue is supplied to said supply circuit energizetion of said windingreduced to a degree slightly higher than that necessary to maintain therelay armature picked up,whereby when said relay armature is picked upitbecomes released on 'a'small reduction in the value of thecurrentsupplied to said supply circuit, a source of direct current, and acircuit controlled by the armature of said principal relay for supplyingener y from said source to said auxiliary relay first winding, wherebyon a change in the position of the armature of the principal relay thearmature oi the auxiliary relay also changes its position, and wherebyin addition on a change in the position oithe" armature of the principalrelay an impulse of energy is induced in the auxiliary relay secondwinding and is supplied therefrom to a winding of the principal relay,the equipment being arranged so that on movement of the armature of theprincipal relay towards either of its positions the impulse of energysupplied to the principal relay winding from said auxiliary relay secondwinding is of such polarity as to assist movement of the armature ofsaid principal relay.

4. In combination, a principal relay having a first and a second windingand having an armature which when in its released position is moved toits picked-up position when said first winding is energized to apredetermined degree, a supply circuit over which energy may be suppliedto said relay first winding, means for supplying to said supply circuitenergy which at one time is of a first value and is effective toenergize said relay winding to said predetermined degree and which atother times is of a second or lower value and is inefiective to energizesaid relay winding .to said predetermined degree, an auxiliary relayhaving a first and a second Winding, means for supplying energy fromsaid auxiliary relay second winding to said principal relay secondwinding, means operative in the first position of the armature of saidauxiliary relay to modify the circuit of the first winding of theprincipal relay so that when energy of said first value is supplied tosaid supply circuit energization of said principal relay first windingis reduced to a degree slightly higher than that necessary to maintainthe relay armature picked up, whereby when said auxiliary relay armatureis in its first position and the principal relay armature is picked upthe principal relay armature becomes released on a small reduction inthe value of the current supplied to said supply circuit, a source ofdirect current, and a circuit controlled by said principal relayarmature for supplying energy from said source to said auxiliary relayfirst winding, whereby on a change in the position of the armature ofthe principal relay the armature of the auxiliary relay also changes itsposition, and whereby in addition on a change in the position of thearmature of the principal relay an impulse of energy is induced in theauxiliary relay second Winding and is supplied therefrom to theprincipal relay second winding, the equipment being arranged so that onmovement of the armature of the principal relay towards either of itspositions the impulse of energy supplied to the principal relay secondwinding from said auxiliary relay secondvwinding is of such polarity asto assist movement of the armature of said principal relay, the circuitfor supplying energy to the auxiliary first winding being arranged sothat when the principal relay armature is picked up the auxiliary relayarmature occupies its first position.

5. In combination, a principal relay having a first and a second windingand having an armature which when in its released position is moved toits picked-up position when said first winding is energized to apredetermined degree, a supply circuit over which energy may be suppliedto said relay first winding, means for supplying to said supply circuitenergy which at one time is of a first value and is effective toenergize said relay winding to said predetermined degree and which atother times is of a second or lower value and is ineffective to energizesaid relay winding to said predetermined degree, an auxiliary relayhaving a first and a second winding, means for supplying energy fromsaid auxiliary relay second winding to said principal relay secondwinding, a source of direct current, a circuit establishedby theprincipal relay armature when picked up to supply energy from saidsource to the first winding of the auxiliary relay, whereby on pickingup of the principal relay armature the auxiliary relay armature ispicked .up and an impulse of energy of one polarity is induced in theauxiliary relay second winding and is supplied therefrom to theprincipal relay second Winding and whereby on release of the principalrelay armature the auxiliary relay armature releases and an impulse ofenergy of the opposite polarity is induced in the auxiliary relay secondwinding and is supplied therefrom to the principal relay second winding,the equipment being arranged so that on movement of the principal relayarmature towards either of its two positions the impulse of energysupplied to the principal relay second winding from said auxiliary relaysecond winding is of such polarity as to assist movement of theprincipal relay armature to such position, and means operative when saidauxiliary relay armature is picked up to modify the circuit of theprincipal relay first winding so that when energy of said first value issupplied to said supply circuit energization of said principal relayfirst winding is reduced to a degree slightly higher than is necessaryto maintain the relay armature picked up, whereby said principal relayarmature when picked up becomes released on a small reduction in thevalue of the current supplied to said supply circuit.

6. In combination, a relay having a first and a second winding andhaving an armature which when in its released position is moved to itspicked-up position when said first winding is energized to apredetermined degree, a supply circuit over which energy may be suppliedto said relay first winding, means for supplying to said supply circuitenergy which at one time is of a first value and is effective toenergize said relay winding to said predetermined degree and which atother times is of a second or lower value and is ineffective to energizesaid relay winding to said predetermined degree, a device having aprimary and a second winding inductively coupled together, means forsupplying energy from said secondary winding to said relay secondwinding, a source of direct current, a circuit established by the relayarmature when picked up to supply energy from said source to said deviceprimary winding, whereby on picking up of said relay armature energy issupplied to said device primary winding and an impulse of energy of onepolarity is induced in the device secondary winding and is suppliedtherefrom to the relay second winding, and whereby on release of saidrelay armature the supply of energy to the device primary winding isinterrupted and an impulse of energy of the opposite polarity is inducedin said secondary winding and is supplied therefrom to the relay secondwinding, the equipment being arranged so that on movement of the relayarmature towards either of its two positions the impulse of energysupplied to the relay second winding from said device secondary windingis of such polarity as to assist movement of the relay armature to suchposition, and means operative when said relay armature is picked up tomodify the circuit of the relay first winding so that when energy ofsaid first value is supplied to said supply circuit energization of saidrelay first winding is reduced to a degree slightly higher than isnecessary to maintain the relay armature picked up, whereby said relayarmature when picked up becomes released on a.

7. In combination, a relay having a first and .a second winding andhaving an armature which when in its released position is'moved to itspicked-up position when said first winding is energized to apredetermined degree, a supply circuit over which energy may besuppliedto said relay first winding, means for supplying to said supplycircuit energy which at one time is voi. a first value and is effectiveto energize said relay winding to said predetermined degree and which atother times is of a second or lower value and is ineffective to energizesaid relay winding to said predetermined degree, a device having aprimary and a secondary winding inductively coupled together, means forsupplying energy from said device secondary winding to said relay secondwinding, a source of direct current, a circuit established in oneposition of the relay armature for supplying energy from said source tosaid device primary winding, whereby on a change in the position of saidrelay armature energization of said device primary winding is varied andan impulse of energy is induced in said device secondary winding and issupplied therefrom to the relay second winding, the equipment beingarranged so that on movement of the relay armature towards either of itstwo posittions the impulse of energy supplied to the relay secondwinding from said device secondary winding is of such polarity as toassist movementof the relay armature to such position, and meansoperative when said relay armature is picked up to modify the circuit ofthe relay first winding .so that when energy of said first value issupplied to said supply circuit energization of said relay first windingis reduced to a degree slightly higher than is necessary to maintain therelay armature picked up, whereby said relay armature when picked upbecomes released on a small reduction in the value of the currentsupplied to said supply circuit.

8. In combination, a principal relay having a core and having a firstand a second winding mounted on said core, said relay also having anarmature which is moved from its released to its picked-up position whenthe fiux density in the relay core is increased to the value presentwhen energy of a predetermined value is supplied to the relay firstwinding, a supply circuit over which energy may be supplied to saidrelay first winding,meansforsupplying to said supply circuit energywhich at one time is of said predetermined value and at other times isof a second or lower value, an auxiliary relay having a first and asecond winding, means for supplying energy from said auxiliary relaysecond winding to the principal relay second winding, a source of directcurrent, a circuit established in the picked-up position of the armatureof the principal relay for supplying energy from said source to theauxiliary relay first winding, whereby on picking up of the principalrelay armature energy is supplied to the auxiliary relay first windingand the armature of said relay picks up and in addition an impulse ofenergy is induced in the auxiliary relay second winding and is suppliedtherefrom to the principal relay second winding, and whereby on releaseof the armature of the principal relay the supply of energy to theauxiliary relay first winding is interrupted and the auxiliary relayarmature releases while animpulse of energy is induced in the auxiliaryrelay second winding and is supplied therefrom to the supplied to theprincipal relay second winding on pickingup of the principal relayarmature 'increasesthe flux in the relay cor and so that the impulse ofenergy supplied to the principal relay second Winding decreases the fluxin the relay core, whereby movement of the relay armature to each ofitspositions is rendered positive, and means operative when the armatureof said auxiliary relay is picked up to modify the circuit of theprincipal relay first winding so that when energy of said first value issupplied to said supply circuit energization of said relay first windingis reduced to a degree slightly higher than is necessary to maintain therelay armature picked up, whereby said relay armature when picked upbecomes released on a small reduction in the value of the currentsupplied to said supply circuit.

9. In combination, .a'relay, means for supplying to a winding of saidrelay energy which at one time is of a value high enough to effectmovement of the relay contacts from their released to their picked-uppositions and at another time is of a value too low to maintain therelay contacts picked up, a first and a second winding inductivelycoupled together, means for supplying energy from said second winding toa winding of said relay, a source of direct current, and a circuitestablished on picking up of the contacts of said relay for supplyingenergy from said source to said first winding, whereby on picking up orreleasing of said relay contacts there is a change in energization ofsaid first Winding and an impulse of energy is induced in said secondwinding and is supplied therefrom to a winding of said relay, theequipment being arranged so that the impulse of energy supplied to therelay winding on movement of the relay contacts towards either of theirpositions is of such polarity as to assist movement of the relaycontacts to such position.

10. In combination, a relay having a first and a second winding, meansfor supplying to said relay first winding energy which at one time is ofa value high enough to effect movement of the relay contacts from theirreleased to their picked-up positions and at another time is of a valuetoo low to maintain the relay contacts picked up,

plying energy from said device secondary Winding to the relay secondwinding, a source of direct current, and a circuit established onpicking up of said relay contacts for supplying energy from said sourcto said device primary winding, whereby on picking up or releasing ofsaid relay contacts there is a change in energization of said deviceprimary winding and an impulse of energy is induced in the secondarywinding of said device and is supplied therefrom to the second windingof said relay, the equipment being arranged so that the impulse ofenergy supplied to the relay second winding on movement ,of the relaycontacts towards either of their positions is of such polarity as toassist movement of the relay contacts to such position.

11. In combination, a principal relay having a first and a secondwinding, an auxiliary relay having a first and a second winding, meanfor supplying to said principal relay first winding energy which at onetime is" of a value high enough to effect movement of the relay contactsfrom their released to their, picked-up p'ositions and at another timeis of a value too low to maintain the relay contacts picked up, meansfor supplying energy from the auxiliary relay second winding to theprincipal relay second winding, a source of direct current, a circuitestablished on picking up of the contacts of the principal relay forsupplying energy from said source to the first winding of the auxiliaryrelay, whereby on picking up or releasing of the contacts of theprincipal relay there is a change in energization of the first windingof the auxiliary relay and an impulse of energy is induced in th secondwinding of said auxiliary relay and is supplied therefrom to the secondwinding of the principal relay, and whereby on a change in the positionof the contacts of the principal relay there i a corresponding change inthe position of the contacts of the auxiliary relay, the equipment beingarranged so that the impulse of energy supplied to the principal relaysecond winding on movement of the contacts of said relay towards eitherof their positions is of such polarity as to assist movement of therelay contacts to such position, and a control circuit governed by acontact of said auxiliary relay.

12. In combination, a principal relay having a first and a secondwinding, an auxiliary relay having a first and a second winding, meansfor supplying to said principal relay first winding energy which at onetime is of a value high enough to efiect movement of the relay contactsfrom their released to their picked-up positions and at another time isof a value too low to maintain the relay contacts picked up, means forsupplying energy from the auxiliary relay second winding to theprincipal relay second winding, a source of direct current, a circuitestablished in one position of the contacts of said principal relay forsupplying energy from said source to the first winding of said auxiliaryrelay, whereby a change in the position of the principal relay contactsis accompanied by a change in the position of the auxiliary relaycontacts, and whereby on a change in the position of the contacts of theprincipal relay an impulse of energy is induced in the auxiliary relaysecond winding and is supplied therefrom to the principal relay secondwinding, the equipment being arranged so that the impulse of energysupplied to the principal relay second winding on movement of thecontacts of said relay towards either of their positions is of suchpolarity as to assist movement of the relay contacts to such position,and a control circuit governed by a contact of said auxiliary relay.

13. In combination, a relay having a winding and having an armaturewhich when in its released position is moved to its picked-up positionwhen said winding is energized to a predetermined degree, a supplycircuit over which energy may be supplied to said relay winding, meansfor supplying to said supply circuit energy which at one time is of afirst value and is effective to energize said relay winding to saidpredetermined degree and which at other times is of a second or lowervalue and is ineffective to energize said relay winding to saidpredetermined degree, means operative when the relay armature is in itspicked-up position to modify the circuit of the relay winding so thatwhen energy of the first value is supplied to said supply circuitenergization of the relay winding is reduced to a degree slightly higherthan that necessary to maintain the relay armature in its picked-upposition, whereby when said armature is in its 75 picked-up position itbecomes released on a small reduction in the value of the currentsupplied to said supply circuit, and means responsive to movement ofsaid relay armature towards either of its positions for momentarilysupplying energy to a winding of said relay, said means being arrangedso that on movement of the relay armature towards its picked-up positionthe energy supplied to the relay winding is of a polarity effective toassist movement of the relay armature to its picked-up position and sothat on movement of the relay armature towards its released position theenergy supplied to the relay winding is of a polarity efiective toassist movement of the relay armature to its released position.

14. In combination, a relay having a first and a second winding andhaving an armature which when in its released position is moved toitspicked-up position when said relay first winding is energized to apredetermined degree, a supply circuit over which energy may be suppliedto said relay first winding, means for supplying to said supply circuitenergy which at one time is .of a first value and is effective toenergize said relay winding to said predetermined degree and which atother times is of a second or lower value and is ineffective to energizesaid relay winding to said predetermined degree, means operative whenthe relay armature is in its picked-up position to modify the circuit ofthe relay first winding so that when energy of the first value issupplied to said supply circuit energization of the relay first windingis reduced to a degree slightly higher than that necessary to maintainthe relay armature in its picked-up position, whereby when said relayarmature is in its picked-up position it becomes released on a smallreduction in the value of the current supplied to said supply circuit,and means responsive to movement of said relay armature towards eitherof its positions for momentarily supplying energy to the relay secondwinding, said means being arranged so that on movement of the relayarmature towards its picked-up position the energy supplied to the relaysecond winding is of a polarity efiective to assist movement of therelay armature to its picked-up position and so that on movement of therelay armature towards its released position the energy supplied to therelay second winding is of a polarity effective to assist movement ofthe relay armature to its released position.

15. In combination, a circuit having a variable voltage impressedthereon, a relay having a first winding on which the voltage of saidcircuit is impressed, a second winding, and an armature, said firstwinding being effective in response to an increase in the voltage ofsaid circuit above a certain value for causing the actuation of thearmature from its dropped-out position toward its picked-up position;means effective in response to the actuation of the armature to itspicked-up position to reduce the eiiectiveness of the first windingwhereby to cause the armature to be dropped-out at substantially thesame circuit voltage as that at which it is picked-up; and means forstabilizing the operation of the armature including means formomentarily energizing the said second winding of the relay when thearmature is actuated to its picked-up position or restored to itsdropped-out position in a manner to insure the retention of the armaturein the position into which it is last moved.

ANDREW J. SORENSEN.

